D. The most substantial reduction was found in the lowland areas, which receive
sediment from the entire catchment. Here, cumulative reduction ranged from 0 to
780 Mg ha
À1 for Scenario B and from 0 to 2,150 Mg ha
À1 for Scenarios C and D.
These figures may appear high, because LUCIA does not distinguish erosion that
originates on a pixel and re-entrained sediments from previous time steps.
To disentangle these effects, we analyzed topsoil depth after 25 years using the
same procedures. On a few of the pixels (~20 in the entire catchment), topsoil
thickness was slightly greater in the baseline as compared to Scenario B and
Scenarios C and D. In all other cases, topsoil was up to 5.3 cm thicker under
Scenario B and up to 20 cm under Scenarios C and D, as compared to the Baseline.
Separating these effects between maize and other land covers showed that other
land uses were hardly affected, revealing that top soil loss affected mainly the
source cells and that sediments travelled through the lowlands, but did not cause a
major entrainment of soils under other land cover types.
Table 10.1 Scenarios tested for plots under maize cultivation
Scenario
Management options
Burning Tillage Cover crop Explanation
Baseline: current
practice
Yes
Yes
No
Fallow vegetation or crop residues are
slashed and burned in the dry
season prior to plowing and sowing
B: Zero tillage without
cover crop
No
No
No
Fallow vegetation is not burned but
mulched; maize is planted in
untilled soil
C: Zero tillage with
cover crop
No
No
Yes
Same as (B), but a perennial legume is
inter-planted with maize to reduce
erosion; suppress weeds and fix
atmospheric nitrogen
D: Cover crop plowed
under
No
Yes
Yes
Same as (C), but the cover crop is
plowed into the soil to improve soil
fertility and ease planting
³20
³19
£–4
£0
16
12
18
14
0
cm
mg ha –1
Fig. 10.6 Difference in sediment loads baseline minus scenario D after year 1 (left), and
difference in topsoil depth scenario D minus Baseline after year 25 (right)
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
381
sediment from the entire catchment. Here, cumulative reduction ranged from 0 to
780 Mg ha
À1 for Scenario B and from 0 to 2,150 Mg ha
À1 for Scenarios C and D.
These figures may appear high, because LUCIA does not distinguish erosion that
originates on a pixel and re-entrained sediments from previous time steps.
To disentangle these effects, we analyzed topsoil depth after 25 years using the
same procedures. On a few of the pixels (~20 in the entire catchment), topsoil
thickness was slightly greater in the baseline as compared to Scenario B and
Scenarios C and D. In all other cases, topsoil was up to 5.3 cm thicker under
Scenario B and up to 20 cm under Scenarios C and D, as compared to the Baseline.
Separating these effects between maize and other land covers showed that other
land uses were hardly affected, revealing that top soil loss affected mainly the
source cells and that sediments travelled through the lowlands, but did not cause a
major entrainment of soils under other land cover types.
Table 10.1 Scenarios tested for plots under maize cultivation
Scenario
Management options
Burning Tillage Cover crop Explanation
Baseline: current
practice
Yes
Yes
No
Fallow vegetation or crop residues are
slashed and burned in the dry
season prior to plowing and sowing
B: Zero tillage without
cover crop
No
No
No
Fallow vegetation is not burned but
mulched; maize is planted in
untilled soil
C: Zero tillage with
cover crop
No
No
Yes
Same as (B), but a perennial legume is
inter-planted with maize to reduce
erosion; suppress weeds and fix
atmospheric nitrogen
D: Cover crop plowed
under
No
Yes
Yes
Same as (C), but the cover crop is
plowed into the soil to improve soil
fertility and ease planting
³20
³19
£–4
£0
16
12
18
14
0
cm
mg ha –1
Fig. 10.6 Difference in sediment loads baseline minus scenario D after year 1 (left), and
difference in topsoil depth scenario D minus Baseline after year 25 (right)
10 Integrated Modeling of Agricultural Systems in Mountainous Areas
381